For what it's worth, and not that anyone wants to study more this summer, but... maybe you can use this info if you are applying next year.
If you want a jump on immunology, I took Immunology through UC Berkeley Extension. It's about $800. They use the same book that Tech does. It was a very tough book to read. The actual course, on the other hand, wasn't too bad (the tests). I procrastinated and did most of the course in the last 4 weeks and I earned an A. However, the teacher was counseling me to drop out and it stressed her to the max that I put it off so long. It is a self study, self paced course, but it is fairly interactive. You must take the final exam between 90 and 180 days from when you signup/pay for the class. Make sure you don't register for a section on campus. The first two exams (or maybe there was only one) are "take home". I think we had a week, after we accessed it online, to send it back. The final exam requires a proctor. I used the testing center at a local college.
Biochem: I don't know what I was going to say about this course. It is not a prereq, buy you may have all heard that it is recommended. They say that students who have taken biochem do better.
Does anyone have any insight on how to prepare for the SOP biochem class?